Winnicott summarized the relationship between mathematics and psychological development in his paper “Sum, I am.”. He focused on the anxieties during the way of being “I am”. During the individuation process that leads to the human unit, names are important. As the name of the self appears, the representation of the mother also becomes clear. Paranoid anxieties emerge at this stage. They borders for the self. Winnicott also explained the danger of exploitation are related to gaining new for the intelligent baby. Adaptation of the mother to her baby is another point that is important for the psychological development of the child. He also suggested solutions for the difficulties about learning mathe- matics according to his observations of the development of the child. In this paper, I especially elaborate on individuation process, para- noia, fairy tale of “The Pied Piper of Hamelin”, loss as a subtraction and adaptation of the mother to her baby with reference to “Sum, I am.”.